This invention pertains generally to the display of video images and particularly to a system of generating a large number of randomly placed dots on a video display of the raster scan type.
Linear-Feedback-Shift-Registers (LFSR's) have been used to produce pseudorandom sequences of binary signals whose uses include the generation of noise signals, use as test signals for transmission paths (U.S. Pat. No. 3,986,168 Anderson), and as code sequences for encoding information (U.S. Pat. No. 3,515,805 Fracassi and Savage). Images for raster scan video displays have been produced through the use of analog delays (U.S. Pat. No. 3,659,284 Rausch), by digital addressing means (U.S. Pat. No. 3,793,483 Bushnell, and pending application Ser. No. 859,937 by present applicant), and through the memory scanning technique of representing each picture element on the screen by a different bit of memory (U.S. Pat. No. 4,026,555 Kirschner et al).
The cost of dot displays using analog delays or digital addressing increases with the number of dots. The cost of a display using the memory scanning technique increases rapidly with screen resolution.